Spark-plug.



A. P. sHAw.1 SPARK PLUG. APPLICATION FILED IULYV A9. |91?.

1,290,372. Patented Jan. 7,1919.

A' Wimax@ A INVENToR.

im @JAM ORNEY.

BY Y

-UNTTED STATES. PATENT OFFICE.

ALBERT PABX SHAW, OF PITTSFIELD, MASSACHUSETTS, IASSIGNOB. TO PITTSFIELD SPARK COIL COMPANY, OF PITTSFIELD, MASSACHUSETTS, CORPORATION OF MASSACHUSETTS.

l Application mea July s. 191'7. serial No. 179.346.

To all lwhom t may concern.' n

Be it known that I, ALBERT 'PARK Sraw, a citizen of the United States of Amerlca, residing in thecity of Pittsfield, county of t6' Berkshire,l and State of Massachusetts, .have

invented certain new and useful Improvements in Spark-Plugs, of which vthe followis a specificatlon.

in e 'his invention relates to. improvements 1n spark plugs forth@ eurpeeof'i ian the vaporous `charge of gasolene or ot er 1n ammable substances, in `anlnternal combustion engine, when an eleotrlc current is passed through'the plug in ther usual manner.

' AnA object of the invention is to provide a spark plug that is especially adapted 'for use in internal combustion engines which are sub1' ect to'hard service condltron's as for'propelling aeroplanes, or, as they are sometimes spoken of aero-motors. Inl thrs. class ,of motors itis ve neceary to provide a plu 'that is thoroug y reliable iny every way an particularly as to breakage and one that will not fail to ignite the charge when the electric current is -passedtherethrough at the 'proper time in the cycle of operation of the motor.' The present ,inventlon com-prises, therefore, a plug that is c om osed of a substance that will not readrly reak, as nuca, and one that is sov constructed that 1t will not become overheated, as by forming the shell portion of the plug with fins thereon for readily radiating the heat. l

Broadly the invention comprises a core that is bu' t up of disks or washers of driit'erent diameters, whereby' shouldered portions between the disks are provided which will readily permit the form-ation of gas tight joints by placing suitable gaskets thereon. A recessed chamber is also provided 1n the lower part of the .body portion of the shell and having therein a bridge or baflle member formed with perforation and through the center of this member is formed an openrng to receive'one of the terminals or electrodes of the plug.

.The invention further comprlses means for radiating the heat from the shell portion of the plug. One form of the invention havmg' two sets of heat rediating ns, one being .located at the lower part of the shell .and the other at the upper end of the/.core

' member.

The invention further comprises means for accurately locating the center ter- Specification of Letters Patent. A

the portion indicated at 18.

SPARK-PLUG.

Patented minal or' electrode and at the same time forming gas-tight joints between the core and Shell. y

Referring to t-he'drafwings:` Y 1 Figure 1i shows a sectional'view` through the axis of the core, the core part being .menrber of the form shown in Fig. 1.

Referring to .the drawmgs in detail, the

60 .shown in full lines, the 'sectional part shows casing of the cylinder of the engine is indi- 4 cated at 1, showing the inner end of the shell l projecting slightly 'beyond the-inner surface 2 thereof, as indicated at 3, the usual threads for securing the plug in place in the casing belng indicated at 4. The casing orvshell proper of the plug is Aindicated at 5 and is formed with a .bridge portion 6 having per'-` forations or openings, 7 -extending therethrough and a centrally arranged opening 8 therein through 4which projects the usual centrally located spark terminal 9 of the.

plug, the otherrterminal IObeng secured to the 'casing 5 'by swagingv or Vother methods. 11 indicates a shouldered portion of the cas' ing 5 with which engages a copper gasket 12. Located above the gasket 12 is a ber or mica disk 13 built up `of mica washers, and

located .above the disk 13 is a second gasket preferably of copper and asbestos, indicated at 14. -15 is a check nut which is formed with threads 16 on its outer surface that engage threads 17 y of the shell 5. When the check nut is turned downward into theshell 5 it will clamp Athe'copper land asbestos gaskets 12 and 14`rigi'dly in place in the shell. The check nut 15, it is to be understood, loosely surrounds the core 18 which is preferably built up of disks of mica of'diferent diameters. IThe lower end of the corejis also preferably formed from disks of mica, as in dicated at 19, but is of smaller diameter than j The upper end of the core 18 is provided with a metallic washer 20 having a threaded hub `portion 20?-, and above this washer is located a radiating fin 21 which is, as shown, formed as a i -part of the cap 22 which cap as shown, is

threaded onto the stem 25, to which the electric cable which carries the spark current is connected.

Located above the bridge 6 is an air space or chamber 23 that communicates with the lower part 24 of the lshell by means of the openings 7 and 8, already referred to. It will be seen from this construction that any' hot gases would |be prevented from accumulating in the space 23, as they can readily escape through the openings 7 and 8 into the interior of the combustionchamber. The bale plate 6 serves the further purpose of preventing the oil in the cylinder from reaching or coming into direct contact with the mica core 19. Arranged below the part 19 of the core is the lower end portion 25 of the electric conducting rod 25 which conveys the spark current from the terminal 22 to the terminal 9 which is swaged into the lower end of the rod 25 at 252 as shown.

The 'portion 26 may be considered the ferrule portion of the rod 25. The upper end of the rod or stem 25 is threaded as shown at 25a which receives the threaded portion 20 of the washer 20, and the threaded porl tion of the cap piece 22, whereby when the washer and cap piece are threaded onto the rod 25 the ferrule portion 26 will be drawn upward tightly against the lower end of the core 19. The core portion 18 will be rigidly clamped therefore between the part 26 and the washer 20. Fig. 3 shows the core portion 1,8 aS' made up of tubular pieces of insulating material, the tube 18 being located within the outer one, as shown. It is to be understood, however, that the core of insulating material may, and preferably is, built up of Washers of insulatingmaterial, preferably mica, as represented in Fig. 1 by 'the' lines 182.

Referring to the construction shown in Fig. 2 the shell 5 is formed with the bridge piece. 6, the openings 7 and 8 and the air chamber 23 above the bridge piece as already described. In this construction the check nut 15 is omitted and the enlarged part 13 of the core is retained in place by means of the bent over part 30. The parts 12, 13,'and`14, as in the construction just referred to are located in the recessed por tion of the shell and gaskets 28 and 29 are use of a check nut. l together vwith the enlarged portion of the located above the upper and lowerends of the parts 12 and 14 of the core. These are held in place by rolling or spinning in the metal as shown at 30 referred to above. This method forms a gas tight joint without the The gaskets 28 and 29,

core serve to centerl the terminal 9 in the opening 8, whereby the distance between the spark terminals will always be the same and thus insure perfect operation of the spark.

It should =be stated that an important feature of my invention is the formation of the `tion of the shell. No

enlarged portion 13 of the core accuratelyfits the enlarged bored-out portion of the shell and, therefore, serves to accurately posltlon'the' spark terminal 9 with relation to the other terminal 10. The check nut 15 further serves to accurately position the core of the plug within the casing. The fins 31 serve to maintain the casing 5 in a cool condition. The additional fin 21 also serves to conduct the heat away from the upper part of the stem or rod 25.

The part 18' of the cone is shown as comprising a tube of insulating material,

whereas the part 18 of the core is formed from disks of mica. y

The spark terminals 9 and 10, it will be observed, are located in the combustion chamber of the cylinder. The bridge portion 6 not only prevents the engine from throwing oil on the insulating material but also furnishes means of locating the sparking points in the explosion chamber of the engine, or, on the cylinder side of such bridge portion.

The spark plug herein described also has the advantage of what might be termed a closed end plug. Such a construction permits the location of the sparking terminals directly within the firing or combustion chamber of the motor.

It will be observed that in Fig. 1 the nut 15 directly engages the upper side of. the shouldered portion of the core and the lower side of the shouldered portion of thecore directly engages the annular shouldered porgaskets of any kind are employed as the mica itself forms a perfect gas tight joint.

What I claim is:

1. In a spark plug the combination of a one-piece shell having its lower end recessed, a perforated bridge spaced away from the end of shell and located in the recessed portion and formed integral with the shell, a shouldered portion on the shell above the recessed portion, a built up core consisting of tubular members formed from disks of insulating material of different diameters, the part of the core of greatest diameter engaging the shoulder portion of the shell, a check nut mounted on the core of insulating material for forcing the same into the shell for forming a as tight joint between the core and the she l, a, conducting rod extending through the core, and an electric terminal extending from the rod through the perforated bridge to coperate with the other spark terminal, and for centering the core, as described.

2. A spark plug comprising, in combination, of a shell, the outer surface of which is formed with heat radiating fins, a core of insulating material located in the shell and formed from disks of insulating material, as mica, said core being of different diameter t0 form shoulders, a shouldered portion on the shell, a checknut engaging the shoulders of the core to force the same against the shouldered portion of the shell and for centering the core, as described, an electric conductorpassing through the core, the upper end of the conductor having a heat radiating fin, means comprising an integral perforated bridge in the lower portion of the shell above the spark terminal to permit the escape of the hot gases formed in and about the terminals of the plug and for preventing the oil in the cylinders from reaching the insulating material composing the core and which extends below the shoulder of the shell, and also for preventing preignition of the charge.

3. In a spark plug, the combination with an inclosing one-piece shell, an integral baille plate with curved surfaces near the lower end thereof for dividing the said portion of the shell into two compartments, a two-part core located in the shell, one part being formed from disks of insulating material of different diameters, a tube within the part of the core composed of disks, a portion of the core between its lower 4and upper ends being of greater diameter than the main body of the core, and designed to center the core in the shell, shoulders on the shell, and means comprising gaskets located above and below the last mentioned portion of the core having the greater diameter for forming gas tight joints between the core and the shell and means comprising a check nut for securing the core in place.

4. A spark plug comprising in combination with a one-piece shell formed with heat radiating fins on its outer surface, of a core located within the shell, a stem passing through the core, a portion of the core being of a diameter equal to the greatest internal diameter of the shell, gaskets engaging this portion of the core, a check nut on the core threaded into the shell and engaging a gasket to center the core and for forming a gas-tight joint between the shell and core, the lower portion of the shell having an integral perforated bridge therein to prevent the pocketing of hot gases about the lower portion of the core, as described.

5. A spark plug comprising an outer onepiec'e shell or body portion, a core within formed from disks of insulating material,

a portion of the core being in one piece and tubular in form, the core having a' stem extending therethrough, its upper end Vbeing threaded'to receive a threaded washer and a threaded cap-piece, the thread of the stem passing through both the washer and cappiece, said cap-piece having a heat radiating fin, the lower end of the core being spaced from the inner surface of the shell, an integral baffle plate to separate the end of the core from the interior of the engine cylinder, means to secure the core in the casing and for forming a gas tight joint between the core and casing.

6. A core construction for spark plugs' formed `from insulating material and of different diameters, means for centering the same in a shell comprising engaging shouldered portions on the core and shell, means for forcing the shouldered portions together,

said shell having a perforated baiiie-plate.

for separating the end of the core from the interior of theengine cylinder casing for the purpose described, a spark terminal on the core extending through the baille plate, means for clamping the insulating material together, heat radiating casing, and spark terminals on the core and casing.

7 A spark plug comprising an outer shell or body portion, a composite core therein composed of tubular members, onelof said members being composed of washers of insulating material of different diameters, the lower end of the shell having a perforated bridge portion to protect the core from oil in the engine cylinder, said shell having its lower end located within the firing or conibustion chamber of the motor, as described, a current conducting rod extending through the core and spark terminals on the shell and rod, the terminal on the rod extending through the bridge portion, and means to secure the core in the shell, said shell and conducting rod having heat radiating fins or projections.

8. A spark plug comprising in combination, a shell or body portion, a core therein, the shell having a perforated bridge or partition at its lower end to serve as a closed end for the shell of the plug to protect-the` core from oil, a shoulder on the-shell and core, a nut loosely mounted on the core and threaded into the shell for engaging the core to secure the same in the shell and for locating the center terminal, as described, a conducting stem passing through the core, a spark terminal secured to the conducting stem and extending through a perforation in the brid e, the other terminal being on the shell, an means to secure the stem in place..

, ALBERT PARK sHAw.

fins on the corc andY 

